For instance, it has been shown that in experimental AMD, aging CX3CR1 deficiency causes microglia to migrate and accumulate in the subretinal space because it lacks the CX3CR-1-CX3CL1 complex, which physiologically maintains microglia homeostasis (Penfold et al., 2001; Minghetti et al., 2008). Here, CX3CR1 is linked to age-related macular degeneration.